Repeated Nasal Challenge in Skin Prick-puncture Negative and Intradermal Positive Dust Mite Allergic Rhinitis Patients

Subjects who have a clinical history of perennial rhinitis symptoms associated with dust exposure or not associated with other perennial allergens, will have a positive challenge with Dermatophagoides pteronyssinus. Subjects will be ppt negative and intradermal skin test positive to Dust p Challenges will be performed with placebo or Dp extract three times daily each for 2 weeks. Primary endpoint after nasal challenge with Dust p Mean Symptom score increase by greater than or equal to 2 from baseline. Secondary Outcomes Mean decrease in PNIF by greater than 15percent from baseline. Mean increase in nasal lavage PGD2 and ECP by greater than 15percent from baseline levels. Correlation between the orthogonol diameter of the wheal and flare of the intradermal skin test and the degree of symptom worsening during the nasal challenge. These results will provide evidence for the continued use of the intradermal skin test in evaluating allergic rhinitis.